Proximity sensors and other electronic devices have long been used to sense when a device or component is operating within predefined tolerances. In many instances, the signals generated by a proximity sensor may be used to selectively enable and disable various portions of a system. For example, if a proximity sensor senses that a device or component is within a predetermined distance of a reference location, this may indicate an undesired configuration. In such an instance, the sensor output signal may be used to disable a system (or portion thereof). Conversely, if a device or component being within a predetermined distance of a reference location is a desired configuration, the sensor output signal may be used to enable a system (or a portion thereof).
Sensors and other electronic devices have been, and continue to be used, on various types of aircraft. Many aircraft structures are now built using relatively lightweight non-conducting composite materials thus providing less shielding against lightning strikes and other types of electromagnetic interference (EMI), such as radio frequency interference. As a result, both EMI specification levels and dielectric strength requirements for systems and components that are installed in these environments have increased. Current state of the art sensors and other circuits typically use filter capacitors for EMI protection. However, the filter capacitors are typically coupled from internal wiring to a chassis and may provide an undesirable path for lightning currents to be conducted into other sensitive electronic equipment connected to the wiring. Presently, electronic circuits that can withstand more hostile lightening and radio frequency EMI environments are not readily available.
Hence, there is a need for EMI protection devices that that can withstand the increasingly difficult lightening and radio frequency EMI environments. The present invention addresses at least this need.